Resin composition for a battery case for secondary battery

Abstract

The invention relates to a resin composition for a battery case for secondary battery, comprising: (a) about 100 parts by weight of a polypropylene type resin having a density of propylene polymer portion of about 0.905 g/cm 3 or more and an MFR of about 0.1 to 12, composing a matrix phase, (b) about 0.5 to 10 parts by weight of component (b-1) or (b-2), composing a dispersed phase polymer, and (c) a hydrogenated block copolymer obtained by hydrogenating a block copolymer; said hydrogenated block copolymer composing a boundary surface between the component a) and the component (b); wherein (b-1) is a hydrogenated block copolymer having a number average molecular weight of about 100,000 or more, in terms of polystyrene, and (b-2) is a high-density polyethylene having a density of about 0.940 g/cm 3 or more.

1. A resin composition for a battery case for secondary battery consisting of:
 (a) about 100 parts by weight of a polypropylene type resin having a density of propylene polymer portion of about 0.905 g/cm 3  or more arid an MFR at 230° C. with a load of 21.18 N of about 0.1 to 12 g/10 min, composing a matrix phrase, 
 (b) about 0.5 to 10 parts by weight of a hydrogenated block copolymer having a number average molecular weight of about 100,000 or more, in terms of polystyrene, as measured by gel permeation chromatography (GPC), and being obtained by hydrogenating a block copolymer comprising at least two polymer blocks A which mainly comprise vinyl aromatic compound units and at least one polymer block B which mainly comprises conjugated diene compound unit(s), wherein the bonded vinyl aromatic compound units has a content of 26 to 55 wt %, composing a dispersed phase polymer, which forms a boundary phase with the matrix phase (a). 
 
     
     
       2. The resin composition for a battery case for secondary battery according to  claim 1 , wherein the density of the propylene polymer portion of the polypropylene type resin of the component (a) is about 0.905 g/cm 3  or more and the MFR of the polypropylene type resin is about 0.1 to 5 g/10 min. 
     
     
       3. The resin composition for a battery case for secondary battery according to  claim 1 , wherein proportion of the component (b) is about 1 to 7 parts by weight. 
     
     
       4. The resin composition for a battery case for secondary battery according to  claim 1 , wherein number average molecular weight of the hydrogenated block copolymer of the component (b) is about 130,000, in terms of polystyrene, as measured by gel permeation chromatography (GPC). 
     
     
       5. The resin composition for a battery case for secondary battery according to  claim 1 , wherein the conjugated diene compound unit(s) in the block copolymer before the hydrogenation for obtaining the hydrogenated block copolymer of the component (b) are butadiene unit(s). 
     
     
       6. The resin composition for a battery case for secondary battery according to  claim 4 , wherein the conjugated diene compound unit(s) in the block copolymer before the hydrogenation for obtaining the hydrogenated block copolymer of the component (b) are butadiene unit(s). 
     
     
       7. A battery case for secondary battery, which directly accommodates therein an electrode and a separator and is formed of a resin composition of  claim 1 . 
     
     
       8. The battery case for secondary battery according to  claim 7 , wherein the density of the propylene polymer portion of the polypropylene type resin of the component (a) is about 0.905 g/cm 3  or more and MFR of the polypropylene type resin is about 0.1 to 5 g/10 min. 
     
     
       9. The battery case for secondary battery according to  claim 7 , which is a battery case for enclosed secondary battery. 
     
     
       10. The battery case for secondary battery according to  claim 8 , which is a battery case for enclosed secondary battery.